Method for continuously extruding netlike structures

ABSTRACT

Method of making a netlike structure of woven or braided construction wherein a series of streams, extruded along each of the opposite sides of a common plane, are transferred to and from respective opposite sides of the common plane alternately with relative movement of the two series of streams in directions substantially parallel to the common plane.

United States Patent Inventor Theodore H. Fairbanks West Chester, Pa.

Appl. No. 825,210

Filed May 16, 1969 Patented Dec. 14, 1971 Assignee FMC CorporationPhiladelphia, Pa.

METHOD FOR CONTINUOUSLY EXTRUDING [56] References Cited UNITED STATESPATENTS 3,331,903 7/1967 Mine 264/103 Primary Examiner- Donald J. ArnoldAssistant ExaminerArthur H. Koeckert Attorneys-Thomas R. O'Malley,George F. Mueller and Eugene G. Horsky ABSTRACT: Method of making anetlike structure of woven or braided construction wherein a series ofstreams, extruded along each of the opposite sides ofa common plane, aretransferred to and from respective opposite sides of the common planealternately with relative movement of the two series of streams indirections substantially parallel to the common plane.

PATENTEU nEm IQYI 3,627,863

' sum 1 BF 3 PATENTEUDECMISYI 3.627353 SHEET 3 [IF 3 METHOD FORCONTINUOUSLY EXTRUDING NETLIKE STRUCTURES The present invention isdirected to a method of making netlike structures, and particularlywoven or braided structures, by extrusion.

US. Pat. No. 3,331,903 discloses a method and apparatus for making a netfrom plastic material by extruding a plurality of pairs of filaments ofplastic material in such a manner that the filaments in each pair arespaced from each other in a first direction and the pairs of filamentsare spaced from each other a given distance in a second direction. Thefilaments of each pair of filaments are revolved at the moment of theirextrusion and before being solidified about an axis extending betweenthe filaments of each pair of filaments so as to twist the filaments ofeach pair together and to thus integrally connect the filaments. One ofthe filaments of each pair of filaments is then moved in a seconddirection a distance equal to the spacing between pairs of filamentswhile continuing the extrusion of the filaments, after which pairs offilaments are again revolved as heretofore described. By continuouslyrepeating the above steps and setting of the extruded filaments ofplastic material, a netlike structure is provided.

Of particular importance in the method described in the above-notedUnited States patent is that the extruded filaments are revolved throughone or more revolutions while they are still in a plastic condition soas to twist and integrally connect or bond such filaments to each otherat their location of twisting.

A primary object of this invention is to provide a new or improvedmethod for making netlike structures having strands or filaments whichare interlaced with each other.

Another object of this invention is a new or improved method for makingcontinuous woven or braided netlike structures by extrusion.

Still another object is the provision of a method for making, byextrusion, woven or braided netlike structures having a variety ofinterlaced strand or filament patterns.

A further object is the provision of a continuous extrusion method formaking woven or braided netlike structures using apparatus which issomewhat similar to that of known construction.

These and other objects are accomplished in accordance with the presentinvention by a method which includes extruding a plurality of pairs ofcontinuous streams of flowable strand-forming material, with the streamsin each such pair being spaced from each other in a first direction andthe pairs of streams being spaced from each other a given distance in asecond direction. The streams of each pair of streams are revolvedthrough an angle of only I80 about an axis extending between therespective streams of each such pair of streams. The'streams of eachsuch pair of streams are then moved relatively in the second directionto arrange at least certain of the streams of each pair of streams intodifferent pairs. The streams of strand-forming material are setconcomitantly with their extrusion. By continuously repeating the abovesequence of movements, with the continuous extrusion of the streams ofstrand-forming material, a netlike structure is produced.

The axis about which the streams of each pair of streams are revolved ispreferably located midway between the respective streams of each suchpair of streams. Further, it is essential that the direction ofrevolution of the pairs of streams be reversed after each relativemovement thereof and that the direction of relative movement of thestreams be reversed after each revolution of the pairs of streams.

Relative movement of the streams of each pair of streams is preferablyeffected by moving the streams of each pair of streams oppositely ofeach other in the second direction. During such movement the streams ofeach pair of streams may be moved a distance equal to one-half of thegiven distance between the pairs of streams in the second direction or afurther multiple thereof. It will be apparent that this relativemovement of the streams of each pair of streams may be varied throughoutthe method. providing it is a multiple of one-half of the given distancebetween the pairs of streams, to provide netlike structures withdifferent strand patterns along their lengths.

In the resulting netlike structure. the strands will be interlaced witheach other to provide a woven or braided construction. Setting of theextruded streams into strands may be effected prior to any contactbetween the extruded streams whereby the interlaced strands will beunbonded at their locations of crossing. Alternatively, the extrudedstreams may be set into strands after such streams have made contactwith each other so that the interlaced strands in the resulting netlikestructure will form integral junctions with each other at theirlocations of crossing without disturbing the woven appearance of suchstrands.

As heretofore mentioned, the apparatus employed in the practice of themethod the present invention is somewhat similar to that as disclosed inUS. Pat; No. 3,331,903. More particularly, the apparatus employed in themethod of the present invention includes a set of spaced nozzles locatedalong each of the opposite sides of a common plane, with each of thenozzles having a single extrusion orifice. The nozzles are preferably oflike size and configuration, with each having an exterior peripherydefined by a semicircular and a flat wall. The locations of theextrusion orifices need not be but are preferably spaced like distancesfrom the common plane and the orifices of the nozzles in each series arespaced equal distances from each other when the straight sides thereofare in the common plane.

Means are provided for continuously delivering fiowable strand-formingmaterial to the nozzle extrusion orifices and for setting the streams ofsuch material which are extruded therefrom. The apparatus also includesmeans for relatively moving or shifting the two sets of nozzlesalternately in upposite directions parallel to the common plane andmeans for revolving aligned nozzles of the two sets of nozzles throughan angle of only with the noules of each pair of such aligned nozzlesbeing revolved about a common axis. Revolu tion of the nozzles is timedto occur alternatively with the relative movement of the sets of nozzlesand is controlled so that each nozzle is revolved in a directionopposite to that in which it was moved during its immediately priorrevolution.

The teachings of the present invention are applicable for use with avariety of materials, which are referred to by the terms plastic" orstrand-forming materials," including materials which are thermoplastic,such as polyamides or superpolyamides, polyesters, polyvinyl chloride,copolymers thereof, polyolefins, cellulose acetates, etc., natural orsynthetic rubbers, thermosetting materials or wet-spinnable materials,such as viscose, cupro-ammonium cellulose, or carboxymethyl cellulose.Such materials may include various additives such as stabilizers, dyes,foaming agents, etc., if so desired. It will be apparent that the mannerby which the extruded streams are set will depend upon the particularmaterial which is being employed.

For a greater understanding of this invention, reference is made to thefollowing detailed description and drawing in which FIG. 1 is a verticalsection taken longitudinally of the apparatus employed in the practiceof the method of the present invention;

FIG. 2 is a horizontal section taken substantially along the lineslI--II of FIG. 1;

FIG. 3 is a partial vertical section taken transversely through theapparatus substantially along the lines Ill-Ill of FIG. 2;

FIG. 4 is a perspective view of one element of the apparatus illustratedin FIGS. 1-3; and

FIGS. 5-12 are diagrammatic illustrations showing the positions ofelements of the apparatus at different stages of the method of thepresent invention.

With reference to the drawing, the apparatus includes a pair of verticalsupport members I5 and 17, side walls 19 and 21, which terminate wellabove the lowermost ends of the support memberslSand l7, and a' top wall23. Flanges 25 and 27 extend inwardly from the lowermost ends of theside walls 19 and 21 and cooperate with walls 29 and 31, respectively,projecting from the opposing surfaces of such side walls to providechannels 33 and 35. Plates 37 and 39, extending through openings 41 and43 in the support members 15 and 17, are mounted for sliding movementalong the channels 33 and 35 and together with the support members 15and 17, side walls 19 and 21 and top wall 23, define a closed chamber45.

A conduit 47 opens into the chamber 45 for delivering flowablestrand-forming material thereto under pressure from a suitable source,not shown. Gaskets are provided in the area of the openings 41 and 43 inthe support members 15 and 17 to prevent leakage of strand-formingmaterial during sliding movement of the plates 37 and 39. A tank 49 isprovided for containing a suitable setting liquid 51 in the area belowthe plates 37 and 39.

In the specific embodiment illustrated, contacting parallel surfaces 53and 55 of the plates 37-and 39 together define a common plane and areeach formed with a series of like, equally spaced, semicircular recesses57 and 59, respectively. Nozzles 61 and 63, corresponding in shape tothe recesses 57 and 59, are positioned within the respective recessesfor movement relative thereto, as hereafter described. The nozzles 61and 63 are of like construction and, as best shown in FIG. 4, eachinclude a flat surface or wall 65, a semicircular wall 67, and a topflange 69 which projects over and rests on the top surface of therespective plates 37 and 39. An extrusion orifice 71 extendslongitudinally of each of the nozzles 61 and 63 and a series of gearteeth 73 are formed from along the outer periphery thereof at a locationso as to be exposed below the bottom surfaces of the plates 37 and 39.

With the flat surfaces 65 of the nozzles 61 and 63 aligned with eachother and with the opposing surfaces 53 and 55 of the plates 37 and 39,at least one of the plates 37 and 39, and the nozzles positionedtherein, are moved or shifted longitudinally. Preferably, both of theplates 37 and 39 are shifted longitudinally in opposite directions toeach other. This relative longitudinal movement of the plates 37 and 39is effected through pins 75 and 77 which project from the respectiveplates 37 and 39 and ride along grooves 79 and 81 formed in the opposingfaces of cams 83 and 85. The cams 83 and 85 are of like construction andare fixed, in 180 out-of-phase relationship, to a shaft 87 which issupported by bearings, such as shown at 89, and is intermittently drivenby suitable means, not shown. As more fully described hereafter, theplates 37 and 39 are moved a distance substantially equal to one-halfthe center-to-center spacing of the respective recesses 57 and 59 orfurther multiple of such spacing so as to move the 'nozzles 61 and 63,which are carried by such plates, into different positions of alignmentwith each other.

Alternately with the longitudinal sliding movement of the plates 37 and39, aligned nozzles carried by such plates are together revolved as aunit through an angle or arc of only 180 so as to move at least some ofthe nozzles 61 and 63 from the respective plates 37 and 39 to the otherthereof. Each revolving movement of the nozzles is in a directionopposite to the previous revolving movement thereof and is effected bygear racks 91 and 93 which mesh with the nozzle gear teeth 71 and areintermittently driven, respectively, by segment gears 95 and 97, whichare fixed to oscillating shafts 99 and 101. The flanges 25 and 27 arerabbeted at 103 to provide, with the plates 37 and 39, suitable guidechannels 105 for the racks 91 and 93. Of particular importance, and forreasons as hereafter described in detail, gear teeth are omitted fromalong opposing sides of the racks 91 and 93, as indicated at 107 and109.

For a clear understanding of the method of the present inventionreference is made particularly to FIGS. -12 of the drawing in which thenozzles 61 and 63 have been identified by capital and lower caseletters, respectively, to better illustrate their movements duringvarious stages of the method.

With the various elements of the apparatus in stationary startingpositions as shown in FIGS. 2 and 5, a flowable strandforming material,such as a molten thermoplastic material, is

delivered into the chamber 45 and is continuously extruded from thenozzle orifices as streams which are set in the liquid 51, which maycool water. The cams 83 and are now operated to shift the plates 37 and39 in opposite directions, as indicated by arrows 111 and 113 intopositions as shown in FIG. 6 whereby the nozzles 13, C, D and E arealigned with nozzles a, b, c and d, respectively. During theabovedescribed movement, the racks 91 and 93 travel with the respectiveplates 37 and 39.

With the plates 37 and 39 now held in stationary positions, the shafts99 and 101 are oscillated whereby the segment gears and 97 drive theracks 91 and 93 in directions as indicated by arrows 1 15 and 117. Thismovement causes aligned pairs of nozzles B-a, C-b, Dc and E-d to revolvein the direction of arrows 119 and into positions as shown in FIG. 7.Since the rack portions 107 and 109, having no gear teeth, are adjacentto the endmost nozzles, namely nozzles A and e, no turning movement isimparted to such nozzles.

The plates 37 and 39 are now again shifted in directions of arrows 121and 123; that is, opposite to their direction of movement shown in FIG.5, with the racks 91 and 93 traveling together with such plate. By thismovement, the plates 37 and 39 are returned to their starting positions,but with nozzles A, a, b, c and d now aligned with nozzles B, C, D, Eand e, respectively, as shown in FIG. 8.

Again the plates 37 and 39 are held stationary, while the racks 91 to 93are driven in the direction of arrows 125, which is opposite to thedirection of their prior movement, as shown in FIG. 6. This shifting ofthe racks 91 and 93 causes all of the aligned pairs of nozzles torevolve 180 as shown by arrows 127 into positions as shown in FIG. 9.

The plates 37 and 39 are now shifted, as heretofore described relativeto FIG. 5, into positions as shown in FIG. 10, after which the alignedpairs of nozzles are revolved l80 by the racks 91 and 93, as previouslydescribed with reference to FIG. 6. With the nozzles now positioned asshown in FIG. 11, the plates 37 and 39 are urged into their originalstarting positions, as described with reference to FIG. 7. All nozzlesare new again in aligned positions, as shown in FIG. 12, are revolved180 by the racks 91 and 93 in the same manner as described previouslywith reference to FIG. 8.

During all of the above-described movements, flowable strand-formingmaterial is continuously extruded as streams from all of the nozzleorifices, which streams may be set into strands prior to or aftercontact therebetween, by the liquid 51. In tracing the paths of thevarious nozzles during their described movements, it will be noted thatthe nozzles, between certain endmost nozzles, are moved parallel to thecommon plane, as defined by the opposing plate surfaces 53 and 55,alternately with their transfer from one side of such common plane tothe opposite side thereof. Further, it will be apparent that eachindividual nozzle, between endmost nozzles, maintains the same directionof travel relative to the common plane after each transfer thereof fromone side of the common plane to the other thereof.

With reference to FIGS. 5-12, following the paths of nozzles a, b and cfor example, it will be noted that the strands formed by the stream ofstrand-forming material issuing from the orifices in such nozzles willbe moved alternately from one side of the common plane to the oppositeside thereof, altemately with their movement to the right. Such strandswill cross with strands which are formed by nozzles 13, C, D and E andwhich are moving to the left, as viewed in FIGS. 5-12. Moreover, sincethe movement of the nozzles a, b, and c to and from opposite sides ofthe common plane are 180 out of phase with that of the nozzles 13, C, Dand E, the strands formed by the nozzles a, b and 0 will be interlacedwith the strands formed by the nozzles B, C, D and E to provide a wovennetlike structure.

As heretofore mentioned, during stages as shown in FIGS. 6, 8, 10 and12, aligned pairs of nozzles are revolved through an angle of only 180so that the strands formed by the nozzles are interlaced or woven ratherthan being twisted together.

Further, setting of the streams extruded from the nozzle orifices may beeffected rapidly to avoid bonding between the crossing strands or may bedelayed until the extruded streams have joined to provide integraljunctions, yet maintain their interlaced or woven pattern.

I claim:

1. A method of making a netlike structure by extrusion including thesteps of extruding a plurality of pairs of continuous streams offlowable strand-forming material, with the streams in each such pair ofstreams being spaced from each other in a first direction and the pairsof streams being spaced from each other a given distance in a seconddirection, revolving the streams of each pair of streams through anangle of only 180 about an axis extending between the respective streamsof each such pairs of streams, relatively moving the streams of eachpair of streams in the second direction to arrange at least certain ofthe streams of each pair of streams into different pairs, setting thestreams into strands concomitantly with their extrusion, and repeatingthe above sequence of movements simultaneously with the relativemovement of the streams of each pairs of streams being reversed aftereach revolution of the pairs of streams and the direction of revolutionof pairs of streams being reversed after each relative movement of thestreams of each pair of streams.

2. A method as defined in claim 1 wherein the streams of each pair ofstreams are extruded along opposite sides of a common plane.

3. A method as defined in claim 1 wherein the extruded streams ofstrand-forming material are set prior to any contact between suchstreams.

4. A method as defined in claim 1 wherein the extruded streams are setafter streams have contacted each other.

5. A method as defined in claim 1 wherein relative movement of streamsof each pair of streams is effected by moving the streams of each suchpair opposite of each other in the second direction.

6. A method as defined in claim 5 wherein the streams of each pair ofstreams are moved in the second direction a distance equal to a multipleof one-half of the given distance.

7. A method as defined in claim 1 wherein the streams of each pair ofstreams are revolved about an axis located midway between the respectivestreams of each such pair of streams.

2. A method as defined in claim 1 wherein the streams of each pair ofstreams are extruded along opposite sides of a common plane.
 3. A methodas defined in claim 1 wherein the extruded streams of strand-formingmaterial are set prior to any contact between such streams.
 4. A methodas defined in claim 1 wherein the extruded streams are set after streamshave contacted each other.
 5. A method as defined in claim 1 whereinrelative movement of streams of each pair of streams is effected bymoving the streams of each such pair opposite of each other in thesecond direction.
 6. A method as defined in claim 5 wherein the streamsof Each pair of streams are moved in the second direction a distanceequal to a multiple of one-half of the given distance.
 7. A method asdefined in claim 1 wherein the streams of each pair of streams arerevolved about an axis located midway between the respective streams ofeach such pair of streams.